Local area networks (LANs) are designed for high speed data transfer between computers in close proximity. A typical LAN is less than a mile in length, usually within a single building, and transfers data at ten megabits per second. LANs often connect to many computers, and a segment of a LAN may interconnect to other LAN segments forming a network. In order to optimize performance and to isolate errors that occur on a LAN, the data being sent over the LAN needs to be monitored.
One way of monitoring the performance of a LAN is to examine all the packets sent on the LAN, classify them into types, and keep records of how many of each type has been sent over a period of time. To monitor the performance of the LAN over time, these statistical records need to be kept and updated periodically to determine how they have changed during the last time interval.
Most local area networks have a person assigned to the function of network manager. One of the responsibilities of the network manager is to monitor a LAN to assess performance and isolate errors. The network manager needs to be able to monitor LAN segment traffic on several segments of the LAN and view data from each segment simultaneously. This often cannot be done if the manager needs to attach an instrument to a remote LAN segment, because of the difficulty of finding the LAN cable used by the segment, and the difficulty in finding a location for attaching the instrument. Therefore, a network manager needs to be able to collect statistics from a remote LAN segment and transfer these statistics to a management node, where the statistics are kept for a historical record.
One prior art solution to this problem is an instrument called the HP LanProbe. This is a specialized instrument which connects to a LAN segment, collects data from the LAN segment, and transfers this data to a personal computer workstation which displays the data. The personal computer workstation can communicate with many different remote LanProbes. Although the LanProbe instrument maintains some statistical history, it is very limited in duration. Another disadvantage of this solution is that the personal computer can communicate with and display statistics from only one LanProbe at a time, forcing comparative analysis to be done manually. Another disadvantage to this solution is that a dedicated LanProbe instrument must be purchased for each LAN segment to be monitored.
Another solution is the traffic program that runs on SUN Microsystems workstations. This program allows a remote SUN workstation to gather the statistics and then have these statistics displayed on a local SUN workstation. This system, however, does not keep historical data so the network manager must actually be running the tool at the time data needs to be viewed. Another disadvantage of this solution is that the remote collection point of the statistics must also be a compatible workstation running the same operating system.
Because of the speeds at which a LAN operates, and the variety of different record types sent over the LAN, there can be a sizable amount of data to save for each sampling of statistics. Also, the sampling rates need to be reasonably fast to get a detailed picture of the LAN operation. The network manager is forced to trade off between sampling slowly enough to cover the desired time interval in the allotted disk space versus sampling often enough to get the desired level of detail. Furthermore, when displaying this data, there are times when the available data needs to be displayed in as much detail as possible, such as for fault diagnosis, and other times when it should be displayed with less detail, such as for trend analysis.
There is need in the art then for a system to collect data from several remote LAN segments, and collect this data into a management node for viewing. There is also a need in the art for correlating the data from the various remote nodes onto a single display. Still another need is to combine historical data in a manner that reduces the amount of storage space necessary to retain the data while still retaining the peak sample information of the original data. Yet another need is to display the information on a display that allows easy display of historical data with an ability to show various time windows and resolutions.